Faculty candidate seminar - Sarah Kang

05/30/2019 - 12:45pm
Eckart 227
Event Description: 


Climate Change and the Hydrological Cycle

DATE:          May 30th, Thursday, 12:45 p.m.  

LOCATION:     Eckart 227
SPEAKER:      Sarah Kang
            Ulsan National Institute of Science and Technology
What determines the ITCZ position?: Energetics framework connecting high-latitude forcing and ITCZ
Interhemispheric differences in top-of-the-atmosphere radiation can cause meridional shifts of the tropical rainbands. For instance, 20th century anthropogenic aerosol emissions, mostly concentrated in the Northern Hemisphere (NH), displaced the Inter-Tropical Convergence Zone (ITCZ) southward. However, recent studies in which radiative perturbations were applied over the Southern Ocean did not show a significant ITCZ displacement. Here, using a hierarchy of coupled models, we demonstrate a previously unrecognized sensitivity of the tropical climate response to the hemisphere in which subpolar radiative forcing occurs. A NH subpolar radiative cooling leads to a clear southward ITCZ shift and a weakening of the Walker circulation, while an equivalent forcing over the Southern Hemisphere (SH) induces only a subtle ITCZ shift together with a strengthening of the Walker circulation. This hemispheric sensitivity arises due to a strong damping effect of Southern Ocean heat uptake, distinct cloud radiative effect responses, as well as the fact that the climatological ITCZ is in the NH. Thus, both future tropical hydrological cycle projections and the interpretation of tropical paleoclimate proxies crucially require detailed knowledge of the radiative forcing spatial pattern.
Faculty Host:  Ian Eisenman (ieisenman@ucsd.edu)
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